The reality of motor abilities and the factors determining the development of motor abilities in the 4225 preschool children from 0 to 6 years old were examined by analyzing such survey and tests as their living environment, situation of play, physique, muscular strength, motor abilities of balance, agility, coordination and rhythm.
　The stepwise multiple regression and the principal factor analysis were applied to the data, and following results were obtained:
　1. Boys are better than girls in the motor abilities of energy system, but girls are better than boys in the motor abilities of cybernetics system.
　2. The motor abilities of energy system develop according to their age, but the motor abilities of cybernetics system remarkably develop in younger children from 3 to 4 years old.
　3. The motor abilities of cybernetics system are more powerfully grown at the nursery school than their own homes, and their friends have a stronger effect on the development of general motor abilities than their own parents.
　4. The four factors, power and muscles, balance and endurance of muscles, coordination and rhythm, flexibility, were extracted as the general factors of motor ability in the preschool children.

DESCENTE SPORTS SCIENCE Vol.5/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE